US2297314A

US2297314A - Drying apparatus

Info

Publication number: US2297314A
Application number: US259743A
Authority: US
Inventors: Offen Bernard
Original assignee: Individual
Current assignee: Individual
Priority date: 1939-03-04
Filing date: 1939-03-04
Publication date: 1942-09-29
Anticipated expiration: 1959-09-29

Description

B. OFFEN 2,297,314

DRYING APPARATUS Filed March 4, 1939 Sept. 29, 1942.

s Sheets-Sheet i INVENTOR Zen/Zara Q em B'Y pg ATTO R N EY Sept. 29, 1942. B. oFFEN 2,297,314

" DRYING APPARATUS Filed March 4, 1939 3 Sheets-Sheet 2 INVENTOR Berna/d We ATTORNEY Sept. 29, 1942. I B. OFFEN 7,

' DRYING APPARATUS Filed March 4 1939 3 Sheets-Sheet 3 INVES fiermzr' 0 an n ATTORNEY Patented Sept. 29, 1942 UNITED STATES PATENT OFFICE DRYING APPARATUS Bernard Offen, Chicago, Ill.

Application March 4, 1939, Serial No. 259,743

6 Claims.

This invention relates to drying, and more particularly, to the drying of web materials such as paper, textiles, metal plating, foils, and the like.

The general object of the invention is to provid an improved apparatus for drying various types of web materials, which enable the necessary drying to be accomplished more quickly and economically than heretofore.

It is another object of the invention to provide apparatus for drying web materials, such as freshly printed paper or the like, which utilize relatively high temperatures but which insure against scorching of or similar damage to such materials. Th high temperatures employed make for rapid and effective drying action, but are at all times prevented from adversely affecting the material being dried.

It is another object of the invention to provide a drying system in which gas burners or the like are employed within an insulated drying hood or chamber through which the material to be dried is assed, the flames from said burners serving to hea to a relatively high temperature air which is passed to said material for contact therewith, the flames themselves being out of contact with said material. In this way, the temperature of the drying air supplied to web material may be raised to the order of 1500 F. or higher, if desired. This hot air, supplied to the material at a suitably high velocity, sweeps the vapors from the material and thus brings about rapid and effective drying.

It is another object of the invention to provid a heating system in which material to be dried is passed through a drying chamber and is contacted by hot air, a great portion Of which is normally recirculated to the chamber after contacting with the material, but substantially all of which is discharged and replaced by relatively cool air whenever the passage of material through the chamber is interrupted. Thus, for example, whenever the web passing through the chamber is halted, relatively cool air is supplied thereto at once to prevent scorching or burning which might otherwise occur due to the high temperature of th chamber interior, although normally a large percentage of the hot air withdrawn from the drying chamber is recirculated thereto in the interest of operating economy.

It is another object of the invention to provide a drying system for drying web materials such as freshly-inked paper or the like, in which steam is employed to advantage in a plurality of ways, in conjunction with a hot air drying chamber through which such material is passed. Thus,

steam may be used to preheat the material as it passes to the chamber, may be used to facilitate heat transfer and thus increase the effectiveness of the dryin air so as to permit the use of lower operating temperatures, and may be used for re,- turning moisture to th material as it leaves the drying chamber. The steam which is mixed with the drying air in the chamber is withdrawn with such air from the chamber and is recirculated "to the chamber.

It is another object Of the invention to provide, in a drying system including a drying chamber, a novel method of and means for generating and/or superheating steam for use in such system. i

It is another object of the invention to provide a system for drying web material or the lik in which heat is supplied to one side of the material while the other sid thereof is adjacent surfaces maintained at a temperature below the charring temperature of the web material.

It is another object of the invention to provide a drying system including a drying chamber, in which leakage of vapors and fumes from the drying chamber into the ambient atmosphere is eifectively prevented at all times.

It is another object of the invention to provide a drying chamber having one or more gas burners, the operation of which are controlled in response to variations in temperature within the chamber and in the speed at which material to be dried is passed through the drying chamber. Thus, in a preferred embodiment of the invention, five burners are provided, and the number of these which are operated is varied in accordance with the temperature within the drying chamber. Whenever the passage of material through the chamber is interrupted, all of the burners are rendered inoperative, such control preferably being automatic rather than manual, so as to assure an adequately prompt response.

It is another object of the invention to provide an apparatus for drying web materials which is compact and essentially self-contained, which may be installed readily and in a short time; which is relatively simple; and which is reliable as well as effective and inexpensive to operate.

Other objects and features of the invention,

.and the particular constructions and combinations of parts employed, will be more apparent from the following description, to be read in connection with the accompanying drawings in which:

Fig. l is a diagrammatic view, partly broken away and partly in section, of a drying apparatus I embodying the invention in a. preferred form, taken on the line l-l of Fig. 2;

Fig. 2 is a plan view, partly in section, of the apparatus of Fig. 1;

Fig. 3 is a longitudinal sectional view taken on the line 3-3 of Fig. 1;

Fig. 4 is a fragmentary view of a portion of the drying chamber, taken similarly to Fig. 3, illustrating a modified construction.

Fig. 5 is a fragmentary view, similar to Fig. 4, illustrating another modified construction; and

Fig. 6 is a view taken'on the line 66 of Fig. 5.

Referring now to the drawings, the numeral 20 designates generally a drying chamber of relatively elongated configuration, as seen in Fig. 3, and of a width suflicient to accommodate web material or the like which is to be passed therethrough. Because of the high temperatures which normally prevail within the chamber during the operation thereof, the interior of the chamber is provided with an insulating lining 2|.

At one end of the chamber 20 and near the rear thereof there is provided an opening 22, through which the web material, designated 23, is adapted to be supplied within the chamber. At the opposite end of the chamber there is similarly provided an opening 24, through which the web material is adapted to be delivered from the chamber'to rollers 25, one or more of which may be cooled, as by maintaining a circulation of cold water therethrough, in order to cool the web material 23 as it issues from the chamber 20.

Within the chamber are positioned a plurality of baflie members 26 extending thereacross. As best seen in Fig. 3, the bailles 26 are generally U-shaped in configuration, thus to provide a plurality of alternately arranged air supply passages 21 and air return passages 28. At one side of the chamber there is provided an exhaust manifold chamber 29 with which the air return passages 28 communicate through suitable openings 30 in end plate 3|. A partition 32, together with plate 3!, segregates manifold chamber 29 from the remainder of the interior of dryer chamber 30.

In the supply passages 21, spaced an appreciable distance from the web 23 and preferably toward the front of chamber 20, and extending across chamber 20, are arranged a plurality of gas supply pipes 33, each provided with an outlet slot or the like 34, which preferably extends substantially throughout the length of the pipe. These slotted pipes constitute burners, and each may be provided with conventional pilot lights (not shown) or the like, for igniting gas deliveredtherefrom. The supply of gas or other fuel to the burners may be controlled in any desired manner. Preferably, however, the pipes are arranged in groups fed by suitable supply manifolds. Thus, as illustrated, the upper three pipes receive fuel from supply line 35, through manifold 36, while the lower two pipes receive fuel from supply line 31, through manifold 38.

Each pipe 33 is provided with a. metallic shield or the like 39 which is arranged to extend on opposite sides of each flame in the direction of the flame and in the direction of air flow through the passages 21. While the flames are thus effective for heating the air delivered through the passages 21, and may in operation extend beyond the ends of the shields, the slots 34 are protected from the force of this air, so that the fuel delivered from the burners may burn smoothly and evenly.

It will be observed that all of the air supply passages except the bottom one are arranged to discharge air in a direction having a component counter to the direction in which the web travels. Thus, the relative velocity of the air with respect to the web is greater than it otherwise would be, and this tends to render the drying air more effective not only as regards heat transfer, but also from the standpoint of breaking up the film of air which extends to form at the surface of the web. The lowermost air passage 21 discharges somewhat in an upward direction so that this air may be exhausted through the lowermost exhaust passage 28, this arrangement being employed to minimize any opportunity for outward leakage through the opening 22.

An air circulating fan 40 draws fresh air from the outdoor atmosphere or any other desired source through connection 4|, and return air from duct 42, and supplies this air, through supply duct 43, to the chamber 20 through an opening 44. The air thus delivered within chamber 20 will pass through the supply passages 21, then contact with the web 23 to effect drying thereof, then pass through exhaust passages 28 and'openings 3D to the manifold chamber 29. Part of this air will then pass through opening 45 to duct 42 and be recirculated. Another portion of the air from manifold chamber 29 will be withdrawn through opening 46 and duct 41 by exhaust fan 48, and exhausted from the system through exhaust duct 49. Whenever reference is made herein to recirculation of air which has contacted the web, it is to be understood that both air and products of combustion are actually recirculated.

At the outlet end of the chamber 20 is formed an auxiliary exhaust chamber 50, into which there pass any gases or fumes which may escape from the chamber 20 through opening 24. Duct 5| provides communication between chamber 50 and duct 41, so that such gases or fumes are exhausted from the system and prevented from entering the ambient atmosphere.

Air inlet connection 4| is provided with suitable dampers 52 for controlling air flow therethrough, and return duct 42 is similarly equipped with dampers 53. The dampers 52 and 53 are differentially interconnected, as by bell-crank 54, so that as dampers 52 open, dampers 53 correspondingly close; and vice versa. Thus, while the volume of air delivered to the drying chamber 20 by fan 40 remains constant, the proportions of fresh and return air may be varied in accordance with operating requirements.

The exhaust duct 41 is also provided with a suitable damper, designated 55, which is preferably linked to the bell-crank 54 or otherwise arranged to be adjusted in accordance with the settings of dampers 52 and 53.

The positions of the

dampers

52, 53 and 55 are adjusted in accordance with the speed at which the web 23 is passed through the drying chamber 20. Since various instrumentalities and arrangements for effecting such operation are well known, no detailed description thereof is deemed required here. For purposes of illustration, however, the bell-crank 54 is shown to be under the control of a damper motor or the like 56, the operation of which is controlled by a speed responsive control device indicated at 51, the connection between the control device 51 and damper motor 55 being indicated by the dash line 58.

Under normal operating conditions, when the web 23 passes through the chamber 20 at relathe air delivered to return manifold chamber 29 will be recirculated. Accordingly, the damper 55 will be relatively closed, so that the exhaust fan 48 handles only about twenty per cent of the maximum air volume it is capable of handling. Also, the dampers 53 are open relatively wide, while fresh air dampers 52 are open but relatively slightly. However, in the event the web is stopped, the dampers are immediately adjusted to the position shown in Fig. 2. Thus, the exhaust damper 55 is wide open, the fresh air dampers 52 are wide open, and the recirculated air dampers 53 are tightly closed. Thus relatively cool fresh air only is circulated in contact with the web, and scorching thereof is avoided, despite the high temperature of the interior of the drying chamber.

It is to be understood, further, that the system is so designed and operated that at all times more air is exhausted through duct 49 than is supplied to the system through connection 4|. Thus, in accordance with the teachings of my copending application, Serial No. 6453, filed February 14, 1935, and issued as Patent No. 2,152,770, outward leakage of gases and fumes from the drying chamber into the ambient atmosphere is effectively prevented.

To control the burner operation in accordance with the speed of the web and to interrupt the burner operation when the web has stopped, the gas supply lines 35 and 31 are respectively provided with valves 59 and 60, underthe control of speed responsive control device 51, through control lines or the like diagrammatically indicates at 58a. Since various control devices of this nature are well known in the art, no detailed description thereof is deemed necessary. If desired, the gas supply lines 35 and 31 may be provided respectively with manual shut-off valves BI and 62.

To maintain desired regulation of the temperature within the drying chamber 20, there is provided a thermostat 63 extending within the front portion of the dryin chamber. Thus situated, the thermostat actually responds to the temperature of the return and fresh air mixture supplied to the chamber by fan 40, but it is to be understoodthat the thermostat may be located at any desired point in the drying chamber or air circulating system. By means of any desired and well known pneumatic or electrical connection, diagrammatically indicated at 64, the thermostat 53 controls the supply of gas to the burners. While suitable control may be effected by modulating the supply of gas to the burners, and/or by rendering the burners serially operative and inoperative, it is preferred to provide the gas lines 35 and 31 with valves 55 and 66, respectively. These valves are so arranged that when relatively little heating is required, only the burners served by manifold 38 will be operative, whereas the burners served by both gas supply manifolds will be operative whenever more heating is required.

At the rear of the chamber 20, extending thereacross behind the web 23, is a steam chamber 61 of which at least the front wall 63 is formed of metal or other substance having a relatively high heat conductivity. Steam or water, preferably the latter, is supplied to the chamber 61 under the control of a suitable valve 69 through supply pipe which connects with the lower portion of the chamber 61. Valve 69 may be regulated in any desired manner, and will be closed when the drying apparatus is inoperative. Water supplied the temperature within the chamber 20 will be of the order of 500-1500 F. This rapid vaporization absorbs a considerable amount of heat and thus serves to cool the web, which tends to be blown against the wall 58 by the air discharged from passages 21. Steam thus generated within chamber 61 is relieved therefrom through pipe 1|, which is preferably provided with a relief branch 12, equipped with a suitable pressure relief valve 13 to prevent the pressure in chamber 61 from rising above a predetermined point. The steam delivered through pipe 1| is preferably controlled by a suitable valve 14. It .will be understood that if steam is supplied to the chamber 51, this steam will be further heated and thus efiect substantial cooling of the web, although the cooling effect will be less than if water were employed.

A branch pipe 15 delivers steamfrom pipe 1! to a preheating roller 15 over which the web ma.-

terial passes enroute to the drying chamber.

Steam condensate is relieved from the, roller 16 through drain connection 11, preferably equipped with a steam trap 18. As illustrated, the preheating roller actuates the speed responsive control device 51, but it is to be understood that the latter may be actuated in any other suitable manner.

A plurality of steam nozzles or sprays 19, fed by pipe 1!, are arranged on opposite sides of the web proximate the outlet opening 24. Thus, moisture is returned to the web material so that it is within the chamber 51 quickly vaporizes, since The steam remaining in pipe H is routed through a superheating coil 80, situated in the drying chamber 20. As illustrated, the coil is positioned toward the front of the chamber, 20, Where it is subject to the action of the relatively hot air supplied to chamber 20 by fan 40. Since this air has a relatively high temperature, the steam in coil 80 is considerably superheated, to a temperature of the order of 500-800 F.

superheated steam from coil 80 is then supplied to manifold 8|, serving a plurality of steam nozzles or sprays 82 arranged in the path of the hot air discharged through supply passages 21 and extending across the width of the drying chamber. As this steam is mixed with the exceedingly hot air passing through passages 21, there is no opportunity for it to condense. However, since the temperature of the web material never, under normal operating conditions, rises above approximately 200 degrees F., condensation occurs as the steam vapor impinges upon the web material. This is especially true of the entering end of the drying chamber 20, since the web material normally enters at a temperature of 70-80 F. The condensation which does occur, however, is exceedingly fine, and does not harm the web material. On the contrary, it aids in bringing about effective drying at lower temperatures than could otherwise be successfully employed since the fine deposit of moisture substantially increases the efficiency of heat transfer. The steam remaining in the air is withdrawn with the return air, so that the major portion of it is returned with the return air delivered to the chamber 20 by the fan 40. In practise, the air is provided with as much steam as it can contain without adversely affecting the oxygen requirements of the burners. By recirculating both steam and hot air to the greatest extent feasible, substantial reduction in operating costs are achieved, it being understood, however, that a portion of the circulated air and steam must be withdrawn and replaced by fresh air and steam in order to maintain such a vapor or fume dilution as will permit effective drying action.

It will be appreciated that by arranging the burners near the web but at a sufficient distance therefrom so that the flames and web are never in contact, the dangers of subjecting web ma terials to direct flames are obviated, while at the same time the heat of the flames is fully utilized, without any appreciable loss, for drying purposes. Moreover, while avoiding the use of direct flames for drying,-there has been provided a system in which effective drying temperatures can be produced almost instantaneously.

Fig. 4 illustrates a modified arrangement for cooling the web, in which ther is provided a partition 83, spaced from the rear of the chamber 20 to provide a plenum chamber 84, and provided with a plurality of apertures 85, preferably in the form of slots extending throughout the width of chamber 20. A fan 86 draws relatively cool air from any desired source, such as the ambient atmosphere or the outdoors, and supplies this air to plenum chamber 84. This air is discharged therefrom through apertures 85 against the rear of web 23, and thus cools the web so as to prevent scorching or burning thereof. The air thus discharged is withdrawn from chamber 20 with the air delivered through supply passages 21. Since this modification of the invention contemplates the elimination of steam chamber 61, steam is supplied to th pipe H from any suitable external source.

Figs. 5 and 6 illustrate a modified steam generating and/or superheating device arranged for cooling the web, as an alternative for the construction illustrated in Figs. 2 and 3. As shown, a supply header 8! is supplied with water or steam by supply pipe 88. A plurality of tubes 8! connect the header 81 with header 90, arranged at the opposite end of drying chamber 2|).

terial, means for circulating through said air supply passageways air and products of combustion withdrawn through said port means and fresh air in controlled proportions, and means for exhausting from the apparatus air and products of combustion which have contacted with said material and are not recirculated to said air supply passages, damper means for regulating the exhaust of air and products of combustion, the inflow of fresh air and the recirculation of air and products of combustion, means for detecting changes in the speed of web travel through the casing and means responsive theretofor controlling the proportions of fresh air and returning air and products of combustion.

2. Ina drying apparatus of the character described, a casing forming a drying chamber,

, delivery, return air port means adapted to receive air and products of combustion which have contacted with said material, means for circulating through said air supply passageways air and Steam generated and/or superheated within the tubes 89 is delivered from header 9!! to pipe II, for utilization as set forth above.

If desired, the burners may be supplied with a combustible mixture of fuel and air, rather than with fuel only, as described above. The supply of such a combustible mixture to the burners renders the burner operation independent of the oxygen content of the air circulated through the drying chamber, and hence the steam content of the circulated air may be substantially higher than where the oxygen of the circulated air is required to support combustion of the burners.

Since many changes may be made in the invention without departing from the scope. thereof, it is intended that all matter set forth in the above description and accompanying drawings be regarded as illustrative and not in a limiting sense.

I claim:

1. In a drying apparatus of the character described for drying inked web material, a casing forming a drying chamber, means for passing through said casing a web to be dried, at "plurality of air supply passageways within said casing adapted to deliver air to said material at a plurality of points, shielded burner means arranged in said air supply passageways and spaced from said points of air delivery, return air port means adapted to receive air and products of combustion which have contacted with said maproducts of combustion withdrawn through said port means and fresh air in controlled proportions, means for exhausting from the apparatus air and products of combustion which have contacted with said material and are not recirculated to said air supply passages, damper means for regulating the exhaust of air and products of combustion, the inflow of fresh air and the recirculation of air and products of combustion, means for detecting changes in the speed of travel of said material through the casing and means responsive thereto for controlling the proportions of return air and products of combustion and fresh air circulated through said air supply passages.

3. In a drying apparatus of the character described, a casing forming a drying chamber, means for passing through said casing material to be dried, a plurality of air supply passagewayswithin said casing adapted to deliver air to said material at a plurality of points, shielded burner means arranged in said air supply passageways and spaced from saidpoints of air delivery, return air port means adapted to receive air and products of combustion which have contacted with said material, means for circulating through said air supply passageways air and products of combustion withdrawn through said port means and fresh air in controlled proportions, means for exhausting from the apparatus air and products of combustion which have contacted with said material and are not recirculated to said air supply passages, damper means for regulating the exhaust of air and products of combustion, the inflow of fresh air and the recirculation of air and products of combustion and means for detecting changes in the speed of travel of said material through said casing for controlling the proportions of return air and products of combustion and fresh air circulated through said air supply passageways and adapted to prevent the recirculation of return air and products of combustion whenever movement of said material through said casing is interrupted, whereby fresh air only is then supplied to said material to avoid overheating thereof.

4. In an apparatus of the character described for drying inked web material, a casing forming a drying chamber, means for passing through said chamber a web to be dried, means for discharging hot air and products of combustion against one side of said web, fluid containing means within said casing on the opposite side of said web and proximate the same, means for supplying fluid to said containing means, the absorption of heat by fluid at a desired temperature in said containing means serving to cool said web, means for delivering fluid in gaseous form from said containing means, and means for discharging said gaseous fluid against said flrst mentioned side of said web.-

5, In an apparatus of the character described for drying inked web materialfa casing forming a drying chamber, means for passing through said chamber a web to be 'dried, means for discharging hot air and products of combustion against one side of said web, fluid containin means within said casing on the opposite side of said web and proximate the same, means for supplying fluid to said containing means, the absorption of heat by fluid at a desired temperature in said containing means serving to cool said web, means for delivering fluid in gaseous form from said containing means, means for discharging said gaseous fluid against said flrst mentioned side of said web, means for recirculating to said casing air and gaseous fluid withdrawn therefrom after contact with said web, and a superheater connected between said fluid containing means and said fluid discharging means and positioned in the path of said recirculated air an gaseous fluid.

6. In an apparatus of the character described, a casing forming a drying chamber, means for passing through said chamber an inked web to be dried, means for discharging hot air and products of combustion against one side of said web, fluid containing means within said casing on the opposite side of said web and proximate the same, means for supplying fluid to said containing means, the absorption of heat by fluid at a desired temperature in said containing means serving to cool said web, means for delivering fluid in gaseous form from said containing means, means for discharging said gaseous fluid against said first mentioned side of said web, means for recirculating to said casing air and gaseous fluid withdrawn therefrom after contact with said web, and a superheater connected between said fluid containing means and said fluid discharging means and positioned in said casing.

BERNARD OF'FEN.

CERTIFICATE OF C0 RRECTION Patent No. 2,297,31h. September 29, 19 42.

BERNARD OFFEN It is hereby certified that error appears in the printed specification of the above numberedpatent requiring c'orrection as iollows: Page 2, first column, line 2, for"Fig. '2" read --Figs. 2 and 5"; line 6, for "Fig. 1" read Figs. land 2-.-; page 1., first -c olumn, line 70, for "material" read -w eb-- line 75, strike out "1115-"; and second column, line' 1, for the le tezflal" read web--; line7, for "material" read --web-; p g 5,.second column, Iine 6, for "an" read -and--; and that the said Letters Patent should be read with this correction therein that the same may conform'to the record'of the case in the Patent Office.

Signed and sealed this 12th day of January, A. D. 1915.

Henry Van Arsdale, -(Sea1) Acting Commissioner of Patents.